function GVerify (options) { // 创建一个图形验证码对象，接收options对象为参数
    this.options = { // 默认options参数值
      id: '', // 容器Id
      canvasId: 'verifyCanvas', // canvas的ID
      width: '40px', // 默认canvas宽度
      height: '15px', // 默认canvas高度
      type: 'number', // 图形验证码默认类型blend:数字字母混合类型、number:纯数字、letter:纯字母
      code: ''
    }
  
    if (Object.prototype.toString.call(options) === '[object Object]') { // 判断传入参数类型
      for (var i in options) { // 根据传入的参数，修改默认参数值
        this.options[i] = options[i]
      }
    } else {
      this.options.id = options
    }
  
    this.options.numArr = '0,1,2,3,4,5,6,7,8,9'.split(',')
    this.options.letterArr = getAllLetter()
  
    this._init()
    this.refresh()
  }
  
  GVerify.prototype = {
    /** 版本号**/
    version: '1.0.0',
  
    /** 初始化方法**/
    _init: function () {
      var con = document.getElementById(this.options.id)
      var canvas = document.createElement('canvas')
      // this.options.width = con.offsetWidth > 0 ? con.offsetWidth : '30'
      // this.options.height = con.offsetHeight > 0 ? con.offsetHeight : '30'
      this.options.width = '112'
      this.options.height = '35'
      canvas.id = this.options.canvasId
      canvas.width = this.options.width
      canvas.height = this.options.height
      canvas.style.cursor = 'pointer'
      canvas.innerHTML = '您的浏览器版本不支持canvas'
      con.appendChild(canvas)
      var parent = this
      canvas.onclick = function () {
        parent.refresh()
      }
    },
  
    /** 生成验证码**/
    refresh: function () {
      var canvas = document.getElementById(this.options.canvasId)
      if (canvas.getContext) {
        var ctx = canvas.getContext('2d')
      }
      ctx.textBaseline = 'middle'
  
      ctx.fillStyle = randomColor(180, 240)
      ctx.fillRect(0, 0, this.options.width, this.options.height)
  
      if (this.options.type === 'blend') { // 判断验证码类型
        var txtArr = this.options.numArr.concat(this.options.letterArr)
      } else if (this.options.type === 'number') {
        var txtArr = this.options.numArr
      } else {
        var txtArr = this.options.letterArr
      }
  
      for (var i = 1; i <= 4; i++) {
        var txt = txtArr[randomNum(0, txtArr.length)]
        this.options.code += txt
        ctx.font = randomNum(this.options.height / 2, this.options.height) + 'px SimHei' // 随机生成字体大小
        ctx.fillStyle = randomColor(50, 160) // 随机生成字体颜色
        ctx.shadowOffsetX = randomNum(-3, 3)
        ctx.shadowOffsetY = randomNum(-3, 3)
        ctx.shadowBlur = randomNum(-3, 3)
        ctx.shadowColor = 'rgba(0, 0, 0, 0.3)'
        var x = this.options.width / 5 * i
        var y = this.options.height / 2
        var deg = randomNum(-30, 30)
        /** 设置旋转角度和坐标原点**/
        ctx.translate(x, y)
        ctx.rotate(deg * Math.PI / 180)
        ctx.fillText(txt, 0, 0)
        /** 恢复旋转角度和坐标原点**/
        ctx.rotate(-deg * Math.PI / 180)
        ctx.translate(-x, -y)
      }
      /** 绘制干扰线**/
      for (var i = 0; i < 4; i++) {
        ctx.strokeStyle = randomColor(40, 180)
        ctx.beginPath()
        ctx.moveTo(randomNum(0, this.options.width), randomNum(0, this.options.height))
        ctx.lineTo(randomNum(0, this.options.width), randomNum(0, this.options.height))
        ctx.stroke()
      }
      /** 绘制干扰点**/
      for (var i = 0; i < this.options.width / 4; i++) {
        ctx.fillStyle = randomColor(0, 255)
        ctx.beginPath()
        ctx.arc(randomNum(0, this.options.width), randomNum(0, this.options.height), 1, 0, 2 * Math.PI)
        ctx.fill()
      }
    },
  
    /** 验证验证码**/
    validate: function (code) {
      var code = code.toLowerCase()
      var v_code = this.options.code.toLowerCase()
      if (code == v_code) {
        return true
      } else {
        return false
      }
    }
  }
  /** 生成字母数组**/
  function getAllLetter () {
    var letterStr = 'a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z'
    return letterStr.split(',')
  }
  /** 生成一个随机数**/
  function randomNum (min, max) {
    return Math.floor(Math.random() * (max - min) + min)
  }
  /** 生成一个随机色**/
  function randomColor (min, max) {
    var r = randomNum(min, max)
    var g = randomNum(min, max)
    var b = randomNum(min, max)
    return 'rgb(' + r + ',' + g + ',' + b + ')'
  }
  
  export {
    GVerify
  }
  
